Thermokarst Lakes Aerial (IMAGE) University of Alaska Fairbanks Caption Researchers observe that roughly 5,000 years ago, thermokarst lakes in ice-rich regions of North Siberia and Alaska began cooling, instead of warming the atmosphere. Pictured: An overhead view of arctic thermokarst lakes. Credit UAF photo courtesy of Katey Walter Anthony Usage Restrictions The University of Alaska Fairbanks makes high-resolution photographs available to the news media for non-commercial uses only. All uses are for one-time, exclusive use in one publication or production only. Due credit will be given to the photographer whose name is provided. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.